As studies are made on synthesis of various monomers and polymers, various polymers are now widely used as a product material. Various characteristics of a polymer such as dynamic characteristics, optical characteristics, and chemical characteristics vary depending on the type of a polymer. When the polymer is industrially used, a homopolymer using one type of a monomer cannot satisfy diverse conditions that are required for a material. As such, a method of using a random copolymer in which many kinds of a monomer are used or a method of mixing heterogeneous polymers is employed. However, for a case in which a random copolymer is used, there is a tendency that characteristics of each copolymerized monomer unit are averaged. In addition, simple mixing of two or more types of a polymer yields separation of polymers that are not miscible with each other (referred to as macro phase separation), and thus it often leads to characteristics that are inferior to those of each monomer unit.
For solving the problems above, known is a block copolymer in which two or more polymer segments are chemically bonded to each other. Since phase separation occurs as polymers are not easily miscible with each other, the phase separation structure has a size of nanometer (referred to as micro phase separation) as they are connected to each other via a chemical bond. For such reasons, characteristics of each polymer segment can be exhibited without inhibiting the characteristics of each polymer segment.
Among the block copolymers, a (meth)acryl block copolymer is being applied for various uses which require transparency or weather resistance.
As a method for producing a (meth)acryl block copolymer, the following method is known (for example, Patent Document 1). First, a macromonomer is produced in advance by using a cobalt chain transfer agent having a very high chain transfer constant. Subsequently, the obtained macromonomer is copolymerized with other (meth)acryl monomer in a solution. However, since this block copolymer is produced by solution polymerization, a recovery process such as re-precipitation is required when the obtained polymer solution is used for an application other than a coating material while the polymer solution can be directly used for use as a coating material. In this regard, from the viewpoint of using a solvent, environmental load is large.